When counting sets that work multiple muscles at once, giving them half credit (instead of full or zero) makes predictions about muscle growth and strength more accurate.

How you count your weightlifting sets—whether you count every little part or just the full sets—can change how we think about how much lifting helps you get stronger versus bigger muscles.

Some trainers count all your lifts to measure workout effort, but this new method gives half credit to exercises that don’t directly work your main muscles—like warm-ups—and it turns out this way predicts muscle growth and strength gains better than the old ways.

Some trainers count all your lifts to measure workout volume, but this claim says a smarter way is to count only the hard sets fully and give half credit to the lighter, supporting ones — and that this method actually predicts muscle growth and strength gains better than the other ways.

Most of what we know about how much to lift and how often comes from young men who already work out—so we don’t know if it works the same way for women, older people, or beginners.

When you're lifting weights, whether you do exercises that target one muscle at a time or ones that work multiple muscles together can change how well we can guess how much muscle you'll build or how much stronger you'll get—and using a special way to measure the workload (called 'fractional') works best for making those guesses.